Occurrence:Chickpeas are generally eaten after cooking, often in a salad, although immature chickpeas are sometimes eaten raw. They can be ground into a paste called hummus for dips. Gram flour or besan is made by grinding chickpeas and is fried or baked to make falafel or farinatas. Chickpeas are often called chana (channa) or leblebi in Indian cuisine.

Allergy Information:Allergy to chickpea has been much less frequently reported than to peanut or soybean. The symptoms of chickpea allergic individuals are similar to those of other food allergies with urticaria (hives) and other reactions of the skin as the most common symptoms. Allergy to chickpea is associated with allergy to other legumes with allergy to lentil being the most frequently reported cross-reaction.

Patil et al. (2001) [713] found that 70, 64, 35, and 26 kDa proteins were major allergens. However, the ELISA results did not correlate well with the DBPCFC results. Only 23 patients showed IgE by ELISA.

Clemente et al. (1999) [714] found that immunoblots gave a typical pattern against 11S globulin with bands at 23 and 35-40 kDa. The 11S globulin is the major protein constituent in chickpea protein isolate.

Clemente et al. (1999) [714] found that immunoblots gave a typical pattern against 11S globulin with bands at 23 and 35-40 kDa. The 11S globulin is the major protein constituent in chickpea protein isolate.

Allergen stability:Process, chemical, enzymatic:Clemente et al. (1999) [714] studied proteolysis of their preparation showing that > 90% of IgE binding could be removed by sequential digestion with two enzymes.

Nature of main cross-reacting proteins:Not known

Allergen properties & biological function:Probably a hexameric seed storage protein. These are cleaved into two disulphide linked subunits of approximately 20 kDa and 40 kDa before forming the hexamer.

Allergen purification:The 11S globulin has been parially purified by Sanchez-Vioque et al (1999) [720] in two forms by either alkaline extraction with sodium sulphite at pH 10.5, precipitation at pH 4.3 followed by washing with ethanol and acetone or alkaline extraction at pH 12.0 and precipitation at pH 4.3. Gel filtration showed that the extraction at pH 10.5 gave a peak at Mr of 216 kDa (compared to 61 kDa for pH 12.0). SDS-PAGE gave a single band at 23kDa and a triplet at 35-40 kDa.

Allergen stability:Process, chemical, enzymatic:The 2S albumin of chickpeas acts as a trypsin and chymotrypsin inhibitor (Vioque et al. 1999 [232]) and it is possible that the presence of the disulfide linkages protect it against enzymatic attack as found for Sin a 1 (Gonzalez de la Pena et al, 1996 [61]). It is also heat and acid stabile.

Nature of main cross-reacting proteins:

Not known

Allergen properties & biological function:The physiological and functional roles of 2S albumins is unclear. Some (e.g. pea or rape seed 2S albumin) including chickpea 2S albumin, have anti-protease activity but many believe the 2S albumins function as seed storage proteins. The amino acid composition of 2S albumin is known, but the sequence has yet to be determined (Vioque J et al. 1999) . It is composed of two peptides (10 kDa +12 kDa) linked by an interchain disulfide bond.

Allergen purification:Chickpea flour is extracted with 0.1 M borate buffer pH 8.3 (1:10 w:v). After centrifugation at 8000xg and dialysis against 25mM sodium citrate buffer pH 4.6 (1:10 v:v) and the precipitated proteins collected ('total albumins'). The extracted albumins were then lyophilised and taken up in 60% (v/v) methanol in which only the 2S albumin is soluble. Proteins soluble in the methanol were concentrated by lyophilization and then purification by ion exchange chromatography on a Mono Q HR5/5 column in 0.05M Tris-HCl, pH 8.0, and eluted with a linear 0.0-0.5M NaCl gradient (Singh et al 1988 [200]; Vioque et al 1999 [232]).